The invention relates to the starting device for an internal-combustion engine.
A starting device for an internal combustion engine is known, comprising a housing, an electric drive motor having a drive shaft, a starting pinion for engagement with a rim gear of the engine, and an intermediate gear making an operative connection between the drive shaft and starting pinion and having a gear shaft. The gear shaft is arranged eccentrically relative to the drive shaft and the starting pinion is arranged longitudinally on the gear shaft movably longitudinally for engagement with the rim gear. A hollow wheel is mounted freely rotatable on the gear shaft by a sleeve and has an internal toothing, in which the free end of the drive shaft mounted on both ends in the housing of the starting device meshes by means of an external toothing. The starting pinion is nonrotatably rigidly connected to the gear shaft and the hollow wheel and the gear shaft are coupled to one another via an elastic connecting element.
In a known starting device of this type, so-called geared starters with an eccentrically arranged hollow-wheel gear (German Offenlegungsschrift 3,100,869), the sleeve in one piece with the hollow wheel of an intermediate gear carries a coarse thread, on which a driver is arranged screwably. The diver is connected via a freewheel to the starting pinion which is arranged rotatably and displaceably on the gear shaft. The driver can be displaced axially by an engaging relay, with the result that the starting pinion can shift into the rim gear of the internal-combustion engine projecting into its displacement path. When the starting pinion has shifted in, the drive motor is switched on. This rotates the starting pinion via the intermediate gear, the driver and the free wheel.
Compression and expansion surges of the internal-combustion engine to be started give rise to shocks in the gear train transmitting the torque of the drive motor, and these can cause fractures in the gear train. This danger is intensified by the intermediate gear, because the shock forces are increased as a result of the step-up ratio of the intermediate gear.
Furthermore, French Published Patent Application FR-A-2,521,641 (Ducellier) published Aug. 19, 1983 describes a starting device or internal-combustions engines with an electric drive motor, in which the hollow wheel and the gear shaft of the intermediate gear are coupled to one another via elastic connecting elements, in order to damp or partially absorb the shocks occurring there and originating from the internal-combustion engine. However, the disadvantage of this solution is that only the gear shaft with the drive pinion is mounted in the housing of the starting device, and therefore the hollow wheel connected to the drive shaft solely via the damping members can come out of place when shocks occur. In the long term, the accuracy and true running of the hollow wheel meshing with the pinion of the drive motor are thereby impaired as a result of the transmitted shocks, and this can lead to increased wear the intermediate gear and even to the failure of the rotation mechanism.